Thinking “Green” When Treating “Pink Puffers” and “Blue Bloaters”—Reducing Carbon Footprint When Prescribing Inhalers

• Asthma
• Carbon Dioxide
• Carbon Footprint
• Climate Change
• COPD
• Drug Prescriptions
• Dry Powder Inhalers
• Environmental Medicine
• Family Medicine
• Global Warming
• Greenhouse Gases
• Metered Dose Inhalers
• Norflurane

Climate change is a serious threat to the foundations of human life, and mitigation of climate change can be considered the main challenge to mankind in the 21^st century. Human-induced climate change is already having a major adverse impact on the health of millions of people worldwide¹. Effective steps to minimize carbon emissions in all areas of human life, especially in the industrialized world, are required to reduce global warming. Ironically, the health care sector is responsible for a significant proportion of greenhouse gas emissions. In the US, an estimated 8 to 10% of national greenhouse gases are emitted by the health care sector^2,3 with production chains for pharmaceuticals being a significant portion. Worldwide, the pharmaceutical industry emits significantly more climate-damaging gases than the automotive industry⁴. Upstream carbon emissions comprise emissions due to drug research, production processes, and transport. Downstream carbon emissions occur at the provider and their patient level and can be reduced by changes in prescription habits such as avoiding unnecessary prescriptions and drug product selection. Preventing illnesses that require drug treatment as well as reducing nonadherence can also reduce downstream carbon emissions⁵. A further step can be taken by providers and patients replacing particularly harmful prescriptions with less harmful ones. Pharmaceutical companies have been reluctant to apply measures to reduce their carbon footprints in the past,⁶ and governments and health insurance companies do not regulate or incentivize the carbon emission reduction of pharmaceutical companies. Health care providers can lead the way with changing prescription patterns that might add economic pressure to foster change. A good case in point here can be asthma and COPD medications.

Propellant gases in metered dose inhalers (MDI) in particular have been a major source of climate-damaging gases in outpatient care. The USA and Puerto Rico have the highest proportion of inhaler doses delivered by MDIs in the western world at 88.5% and 90.4%, respectively⁷. When first introduced, chlorofluorocarbons were used as propellant gases, but their use was banned under the Montreal Protocol 1989 due to their harmful effect on the ozone layer⁸. However, the now frequently used hydrofluorocarbon-based propellants norflurane and aplaflurane have a devastating impact on the climate^7,9. These propellant gases disintegrate very slowly, and thus allow solar radiation in the upper atmosphere to penetrate to the earth’s surface but trapping reflected emissions and reradiating heat energy back toward the earth.¹⁰

A German guideline on climate-friendly prescription of asthma medication recently released by the German College of General Practitioners and Family Physicians estimated that replacing MDI with dry powder inhalers reduces the CO₂ footprint of a typical patient by 455 kg CO₂ for each patient/year. This reduction is more than changing to a vegetarian diet (-440 kg CO₂) or taking a 1250 mile airline flight (-210 kg CO₂).¹¹

Beta₂-agonists and inhaled corticosteroids, the key components of asthma drug treatment guidelines¹² are available as dry powder inhalers (DPI). For treatment of chronic obstructive pulmonary disease (COPD),¹³ long-acting anticholinergics and combination products are available as DPIs or soft mist inhalers (SMI). In addition, some drugs may also be administered using nebulizers (Table 1).

Despite the different application techniques, the efficacy between MDI and DPI medications is considered equivalent in current asthma and COPD guidelines. Some research suggest that drug adherence is higher among asthma patients using DPI than those using MDI.¹⁴ Although the nebulization of the inhalation powder requires a flow of breath against a resistance, we could not find any evidence in the existing literature that this is associated with a feeling of unease in patients. Regardless of which inhaler type is preferred, providers should be aware that errors in inhaler technique are very common¹⁵ and associated with reduced symptom control and increased risk of exacerbations¹⁶. This should encourage providers to regularly check in with patients to demonstrate the correct use of the prescribed inhaler. As inadequate skill in the use of asthma inhalation devices is also frequent among health care professionals¹⁷, external education resources, for example, YouTube videos showing the correct use, can be considered. DPI should not be used in children under 4 years of age with asthma, as their respiratory volume is not sufficient to inhale the powder. In such cases, MDIs with spacers are still recommended¹⁸. For patients with impaired peak inspiration flow rates <60L/min that can be found in elderly patients or patients with severe or exacerbated COPD, MDIs, mist inhaler or nebulized therapy should be considered.¹⁹

Although there is a strong case for prescribing DPIs rather than MDIs for climate change reasons, implementation of the recommendation should not be automatic but should take into account patient preference and willingness and ability to use DPIs safely. Organizations such as the Arthritis Foundation provide guidance for medical devices for patients with physical limitations that can be used in optimizing product selection. From a practical point of view, changing an ongoing and efficient inhaler therapy should be well considered, weighing the pros and cons, and always discussed with the patient in the context of shared decision-making. There is scarce research on patient and health care provider openness to medication changes in favor of climate protection. Although generic DPIs are becoming available, potential barriers might exist for patients involving copayments and insurance prior authorization requirements. Importantly, in a recent representative study 65%²⁰ of Americans agreed with the statement that citizens should do more to address global warming. This opens a window of opportunity for including climate change in medical decision-making and drug therapy changes that patients may welcome.

• Received for publication August 29, 2022.
• Revision received November 3, 2022.
• Accepted for publication November 8, 2022.